diff --git a/.github/workflows/build-ilspy.yml b/.github/workflows/build-ilspy.yml
index 136ff73b4..7804334c3 100644
--- a/.github/workflows/build-ilspy.yml
+++ b/.github/workflows/build-ilspy.yml
@@ -39,7 +39,11 @@ jobs:
         submodules: true
         fetch-depth: 0
 
-    - name: Setup .NET Core
+    - name: Setup .NET Core 3.1
+      uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: '3.1.x'
+    - name: Setup .NET 5.0
       uses: actions/setup-dotnet@v1
       with:
         dotnet-version: '5.0.x'